Emergency service and hosting network access restriction

ABSTRACT

A method of handling a service request from a UE camped on a CAG cell with emergency PDU session is proposed, where the UE is not authorized to access the current CAG cell. When the UE-maintained CAG related configuration is not synchronized with the NW-maintained CAG related configuration, the UE may try to access a CAG cell and sends a service request, but the NW may determine that the CAG cell is not suitable. Because the UE has an existing emergency PDU session, the network will accept the service request, and locally releases all non-emergency PDU sessions associated with 3GPP access. Specifically, the network will locally release SA non-emergency PDU sessions associated with 3GPP access, or MA PDU sessions with only 3GPP access user-plane resources, or 3GPP user-plane resources of MA PDU sessions with both 3GPP and non-3GPP access user-plane resources.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 from U.S.Provisional Application No. 63/336,362, entitled “Local Service Providedby NPN (PNI-NPN or SNPN-NPN) (NPN for localized services)”, filed onApr. 29, 2022, the subject matter of which is incorporated herein byreference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless mobilecommunication network, and, more particularly, to methods for emergencyservice and hosting network access restriction.

BACKGROUND

A Public Land Mobile Network (PLMN) is a network established andoperated by an administration or recognized operating agency (ROA) forthe specific purpose of providing land mobile communication services tothe public. PLMN provides communication possibilities for mobile users.A PLMN may provide service in one or a combination of frequency bands.Access to PLMN services is achieved by means of an air interfaceinvolving radio communications between mobile phones and base stationswith integrated IP network services. One PLMN may include multiple radioaccess networks (RAN) utilizing different radio access technologies(RAT) for accessing mobile services. A radio access network is part of amobile communication system, which implements a radio access technology.Conceptually, RAN resides between a mobile device and providesconnection with its core network (CN). Depending on the standard, mobilephones and other wireless connected devices are varyingly known as userequipment (UE, i.e., MS), terminal equipment (TE), mobile stations (MS,i.e., UE), mobile termination (MT), etc. Examples of different RATsinclude 2G GERAN (GSM) radio access network, 3G UTRAN (UMTS) radioaccess network, 4G E-UTRAN (LTE), 5G new radio (NR) radio accessnetwork, NG-RAN (Next-Generation RAN), and other non-3GPP access RATincluding WiFi.

As compared to PLMN, a non-public network (NPN) is a network fornon-public use. An NPN is either a Stand-alone Non-Public Network(SNPN), i.e., operated by an NPN operator and not relying on networkfunctions provided by a PLMN; or a Public Network Integrated NPN(PNI-NPN), i.e., a non-public network deployed with the support of aPLMN. A Credentials Holder (CH) may authenticate and authorize access toan SNPN separate from the Credentials Holder. The combination of a PLMNID and Network identifier (NID) identifies an SNPN. A UE may be enabledfor SNPN.

PNI-NPNs are NPNs made available via PLMNs e.g., by means of dedicatedDNNs, or by one (or more) Network Slice instances allocated for the NPN.When a PNI-NPN is made available via a PLMN, then the UE shall have asubscription of the PLMN in order to access PNI-NPN. As network slicingdoes not enable the possibility to prevent UEs from trying to access thenetwork in areas where the UE is not allowed to use the Network Sliceallocated for the NPN, Closed Access Groups can be used to apply accesscontrol for PNI-NPN. A Closed Access Group (CAG) identifies a group ofsubscribers who are permitted to access one or more CAG cells associatedto the CAG. CAG is used for the PNI-NPNs to prevent UE(s), which are notallowed to access the NPN via the associated cell(s), from automaticallyselecting and accessing the associated CAG cell(s). CAG is used foraccess control e.g., authorization at cell selection and configured inthe subscription as part of the Mobility Restrictions. A CAG isidentified by a CAG Identifier which is unique within the scope of aPLMN ID.

Local or Localized services are services that are localized (e.g.,provided at specific/limited area and/or are bounded in time). Alocalized service provider is an application provider or a networkoperator who make their services localized and to be offered to end uservia a hosting network. A hosting network is a network that provides(access for) Localized services, and a hosting network can be an SNPN ora PNI-NPN, while a home network is network owning the current in usesubscription or credential of the UE. Home network can be eitherHome-PLMN or Subscribed-SNPN. End user can enable or disable to accessLocalized services. If the end user disables to access Localizedservices, the UE (i.e., MS) may not access an NPN providing access forLocalized services.

For providing (access for) Localized services to UE, UE needs to be ableto discover, select and access an NPN (as hosting network) providingaccess for Localized services.

SUMMARY

A method of handling a service request from a UE camped on a CAG cellwith emergency PDU session is proposed, where the UE is not authorizedto access the current CAG cell. When the UE-maintained CAG relatedconfiguration is not synchronized with the NW-maintained CAG relatedconfiguration, the UE may try to access a CAG cell and sends a servicerequest, but the NW may determine that the CAG cell is not suitable.Because the UE has an existing emergency PDU session, the network willaccept the service request, and locally releases all non-emergency PDUsessions associated with 3GPP access. Specifically, the network willlocally release SA PDU sessions associated with 3GPP access, or MA PDUsessions with only 3GPP access user-plane resources, or 3GPP user-planeresources of MA PDU sessions with both 3GPP and non-3GPP accessuser-plane resources.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a communication system having a Public LandMobile Network (PLMN), a Stand-alone Non-public Network (SNPN), and aPublic Network Integrated NPN (PNI-NPN) supporting (hosting) network andcell selection with Localized services in accordance with one novelaspect.

FIG. 2 illustrates simplified block diagrams of a user equipment and anetwork entity in accordance with embodiments of the current invention.

FIG. 3A illustrates a first embodiment of a 5G system architecture withaccess to SNPN using credentials from credentials holder.

FIG. 3B illustrates a second embodiment of a 5G system architecture withaccess to SNPNs using credentials from credentials holder.

FIG. 4 illustrates an example of NG-RAN modes which broadcast certaininformation in order to provide access to SNPNs.

FIG. 5A illustrates an example of an SNPN-enabled UE that is configuredwith 2 SNPN subscriptions (i.e., 2 subscribed SNPNs in the “list ofsubscriber data”).

FIG. 5B illustrates an example of an SNPN-enabled UE that is configuredwith 2 PLMN subscriptions (i.e., 2 USIMs).

FIG. 6 illustrates Network selection in SNPN access mode with automaticSNPN network selection and manual SNPN network selection.

FIG. 7A illustrates a first embodiment of network and cell selection andaccess control of CAG cells for PNI-NPN (CAG), where access to a CAGcell is accepted.

FIG. 7B illustrates a second embodiment of network and cell selectionand access control of non-CAG cells (public cells), where access to aPLMN is accepted.

FIG. 8A illustrates a first embodiment of network and cell selection andaccess control of CAG cells for PNI-NPN (CAG), where access to a CAGcell is rejected.

FIG. 8B illustrates a second embodiment of network and cell selectionand access control of non-CAG cells (public cells), where access to aPLMN is rejected.

FIG. 9A illustrates one example of UE to discover, select and access NPN(as hosting network) providing access for Localized services usingvalidity information.

FIG. 9B illustrates another example of UE to discover, select and accessNPN (as hosting network) and receive localized services using validityinformation associated with an SNPN.

FIG. 9C illustrates different examples of UE to discover, select andaccess NPN (as hosting network) and receive localized services usingvalidity information associated with a CAG (of a PLMN).

FIG. 10A illustrates a first example of accessing SNPN (as a hostingnetwork) providing access for Localized services, where access isaccepted.

FIG. 10B illustrates a second example of accessing SNPN (as a hostingnetwork) providing access for Localized services, where access isrejected.

FIG. 11A illustrates a first example of accessing PNI-NPN/CAG (as ahosting network) providing access for Localized services, where accessis accepted.

FIG. 11B illustrates a second example of accessing PNI-NPN/CAG (as ahosting network) providing access for Localized services, where accessis rejected.

FIG. 12 illustrates a sequence flow between a UE and a 5GS when UE isaccessing a CAG cell with un-synchronized CAG related configuration andemergency PDU session in accordance with one novel aspect.

FIG. 13 illustrates an example of handling a service request from a UEcamped on a CAG cell with emergency PDU session, where the UE is notauthorized to access the current CAG cell.

FIG. 14 is a flow chart of a method for handling a service request froma UE camped on a CAG cell with emergency PDU session, where the UE isnot authorized to access the current CAG cell in accordance with onenovel aspect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 schematically shows a communication system 100 having a PublicLand Mobile Network (PLMN) 110, a Stand-alone Non-public Network (SNPN)120, and a Public Network Integrated NPN (PNI-NPN)/CAG 130 providingaccess for Localized services in accordance with one novel aspect. PLMNnetwork 110 comprises control plane functionalities, user planefunctionality (e.g., UPF), and applications that provides variousservices by communicating with a plurality of user equipments (UEs)including UE 101. Serving base station gNB 112 belong to part of a radioaccess network RAN 140. RAN 140 provides radio access for UE 101 via aradio access technology (RAT). An access and mobility managementfunction (AMF) in PLMN 110 communicates with gNB 112. UE 101 may beequipped with a radio frequency (RF) transceiver or multiple RFtransceivers.

SNPN network 120 comprises control plane functionalities, user planefunctionality (e.g., UPF), and applications that provides variousservices by communicating with a plurality of user equipments (UEs)including UE 101. The combination of a PLMN ID and Network identifier(NID) identifies an SNPN. Serving base station gNB 122 belongs to partof RAN 150. RAN 150 provides radio access for UE 101 via a RAT. An AMFin SNPN 120 communicates with gNB 122. SNPN 120 is operated by an NPNoperator and does not rely on network functions provided by a publicnetwork. A Credentials Holder (CH) may authenticate and authorize accessto an SNPN separate from the Credentials Holder. NG-RAN nodes whichprovide access to SNPNs broadcast the following information: One ormultiple PLMN IDs, and a List of NIDs per PLMN ID identifying thenon-public networks NG-RAN provides access to (123). An SNPN-enabled UEis configured with PLMN ID and NID (SNPN ID) of the subscribed SNPN, andan SNPN-enabled UE that supports access to an SNPN using credentialsfrom a Credentials Holder may additionally be configured withinformation for SNPN selection (SNPN selection information orconfiguration) and registration using the SNPN subscription or usingPLMN subscription (USIM) (in SNPN access mode) (102).

PNI-NPN (CAG) network 130 comprises control plane functionalities(optional, it may rely on PLMN's control plane functionality), userplane functionality (optional, it may rely on PLMN's user planefunctionality), and applications that provides various services bycommunicating with a plurality of user equipments (UEs) including UE101. PNI-NPN (CAG) 130 is a non-public network deployed with the supportof a PLMN, PLMN 110, by sharing e.g., RAN/gNB 1112 and e.g., controlplane functionalities. A Closed Access Group (CAG) identifies a group ofsubscribers who are permitted to access one or more CAG cells associatedto the CAG. CAG is used for the PNI-NPNs to prevent UE(s), which are notallowed to access the NPN via the associated cell(s), from automaticallyselecting and accessing the associated CAG cell(s). A CAG is identifiedby a CAG Identifier which is unique within the scope of a PLMN ID. A CAGcell broadcasts one or multiple CAG Identifiers per PLMN (113), and a UEis configured with CAG related configuration/information (e.g., an CAGinformation list containing list of allowed CAGs per PLMN) (102).

Local or Localized services are services that are localized (i.e.,provided at specific/limited area and/or are bounded in time (a specificperiod of time)). A localized service provider is an applicationprovider or a network operator who makes their services localized and tobe offered to end user via a hosting network. A hosting network is anetwork that provides access for localized services and can be an SNPNor a PNI-NPN, while a home network is network owning the current in usesubscription or credential of the UE. In the example of FIG. 1 , bothSNPN 120 and PNI-NPN (CAG) 130 can be a hosting network providing accessfor Localized services to UE 101.

A URSP rule may include an association of the UE application and the DNNor network slice which is meant for a specific localized service. A URSPrule can also include “Route Selection Validity Criteria” (Time Windowand/or a Location Criteria Validity Conditions) with the time/locationdefined for the specific localized service. The LADN (Local Access DataNetwork) can also be used for enabling the UE access to localizedservice.

To enable a PNI-NPN or SNPN to provide access to localized services, thePNI-NPN or SNPN operator configures the network with informationenabling the UEs to access the localized services according to validityof the localized services, and the information is determined inagreement with the localized service provider, e.g.: (a) Identificationof each localized service, e.g. to be used in URSP rules; (b) validitycriteria/restriction for each localized service, e.g., the validity oftime duration and/or (area of) location.

When localized services in a network are completed, all UEs registeredwith the network are expected to be moved to other network or to othercells within the same network. The other network can be HPLMN, VPLMN oranother SNPN. UE can stop using the network resources for localizedservices for numerous reasons, e.g.: (a) Localized services in a networkare completed; (b) Validity conditions of network selection informationare no longer met; (c) The user decides to stop using the localizedservices before they are completed (e.g., end user disables to accessLocalized services); (d) A policy decision is taken by the network, withthe effect that the UE is deregistered before the localized services arecompleted. Validity information or restrictions or criteria orconditions (103) are provided or configured to UE as part of thelocalized service information, which are used to restrict the UE'saccess of the SNPN/PNI-NPN (as hosting network) providing access forLocalized services. For providing localized services to UE, UE needs tobe able to discover, select and access a SNPN/PNI-NPN (as hostingnetwork) providing access for the Localized services. The discoverymechanism is based on provisioning or configuring the UE withappropriate information.

FIG. 2 illustrates simplified block diagrams of wireless devices, e.g.,a UE 201 and network entity 211 in accordance with embodiments of thecurrent invention. Network entity 211 may be a base station combinedwith an AMF. Network entity 211 has an antenna 215, which transmits andreceives radio signals. A radio frequency RF transceiver module 214,coupled with the antenna, receives RF signals from antenna 215, convertsthem to baseband signals and sends them to processor 213. RF transceiver214 also converts received baseband signals from processor 213, convertsthem to RF signals, and sends out to antenna 215. Processor 213processes the received baseband signals and invokes different functionalmodules to perform features in base station 211. Memory 212 storesprogram instructions and data 220 to control the operations of basestation 211. In the example of FIG. 2 , network entity 211 also includesa set of control functional modules and circuit 290. Registrationcircuit 231 handles registration and mobility procedure. Sessionmanagement circuit 232 handles session management functionalities.Configuration and control circuit 233 provides different parameters toconfigure and control UE.

Similarly, UE 201 has memory 202, a processor 203, and radio frequency(RF) transceiver module 204. RF transceiver 204 is coupled with antenna205, receives RF signals from antenna 205, converts them to basebandsignals, and sends them to processor 203. RF transceiver 204 alsoconverts received baseband signals from processor 203, converts them toRF signals, and sends out to antenna 205. Processor 203 processes thereceived baseband signals and invokes different functional modules andcircuits to perform features in UE 201. Memory 202 stores data andprogram instructions 210 to be executed by the processor to control theoperations of UE 201. Suitable processors include, by way of example, aspecial purpose processor, a digital signal processor (DSP), a pluralityof micro-processors, one or more micro-processor associated with a DSPcore, a controller, a microcontroller, application specific integratedcircuits (ASICs), file programmable gate array (FPGA) circuits, andother type of integrated circuits (ICs), and/or state machines. Aprocessor in associated with software may be used to implement andconfigure features of UE 201.

UE 201 also comprises a set of functional modules and control circuitsto carry out functional tasks of UE 201. Protocol stacks 260 compriseNon-Access-Stratum (NAS) layer to communicate with an AMF entityconnecting to the core network, Radio Resource Control (RRC) layer forhigh layer configuration and control, Packet Data ConvergenceProtocol/Radio Link Control (PDCP/RLC) layer, Media Access Control (MAC)layer, and Physical (PHY) layer. System modules and circuits 270 may beimplemented and configured by software, firmware, hardware, and/orcombination thereof. The function modules and circuits, when executed bythe processors via program instructions contained in the memory,interwork with each other to allow UE 201 to perform embodiments andfunctional tasks and features in the network. In one example, systemmodules and circuits 270 comprise registration circuit 221 that performsregistration and mobility procedure with the network, a network and cellselection circuit 222 for performing network and cell selection, aPLMN/PNI-NPN(CAG)/SNPN information maintenance circuit 223 that handlesthe adding, removing, and resetting of one or morePLMN/PNI-NPN(CAG)/SNPN information in SIM/USIM and/or in UE(non-volatile) memory (source of the information may come from signalingas well), a config and control circuit 224 that handles configurationand control parameters. Note that the network selection and registrationrelated information, such as HPLMN, Operator Controlled PLMN/SNPNSelector list, User Controlled PLMN/SNPN Selector list, may be stored inSIM/USIM 225 and/or in UE (non-volatile) memory.

SNPN

FIG. 3A illustrates a first embodiment of a 5G system architecture withaccess to SNPN using credentials from credentials holder. FIG. 3Adepicts the 5G System architecture for SNPN with Credentials Holderusing AAA Server for primary authentication and authorization. The AUSFand the UDM in SNPN may support primary authentication and authorizationof UEs using credentials from a AAA Server in a Credentials Holder (CH).The SNPN in FIG. 3A can be the subscribed SNPN for the UE (i.e. NG-RANbroadcasts SNPN ID of the subscribed SNPN). As a deployment option, theSNPN in FIG. 3A can also be another SNPN than the subscribed SNPN forthe UE (i.e. none of the SNPN IDs broadcast by NG-RAN matches the SNPNID corresponding to the subscribed SNPN). The NSSAAF deployed in theSNPN can support primary authentication in the SNPN using credentialsfrom Credentials Holder using a AAA Server (as depicted) and/or theNSSAAF can support Network Slice-Specific Authentication andAuthorization with a Network Slice-Specific AAA Server (not depicted).

FIG. 3B illustrates a second embodiment of a 5G system architecture withaccess to SNPNs using credentials from credentials holder. FIG. 3Bdepicts the 5G System architecture for SNPN with Credentials Holderusing AUSF and UDM for primary authentication and authorization andnetwork slicing. An SNPN may support primary authentication andauthorization of UEs that use credentials from a Credentials Holderusing AUSF and UDM. The Credentials Holder may be an SNPN or a PLMN. TheCredentials Holder UDM provides to SNPN the subscription data.

FIG. 4 illustrates an example of NG-RAN mode(s) which broadcasts certaininformation in order to provide access to SNPNs. A Credentials Holder(CH) may authenticate and authorize access to an SNPN separate from theCredentials Holder. For SNPN identification, the combination of a PLMNID and Network identifier (NID) identifies an SNPN. The NID supports twoassignment models. Under self-assignment model, NIDs are chosenindividually by SNPNs at deployment time (and may therefore not beunique) but use a different numbering space than the coordinatedassignment NIDs. Under coordinated assignment model, NIDs are assignedusing one of the following two options: 1) The NID is assigned such thatit is globally unique independent of the PLMN ID used; or 2) The NID isassigned such that the combination of the NID and the PLMN ID isglobally unique.

The Group IDs for Network Selection (GIN) supports two assignmentmodels. Under self-assignment model, GINs are chosen individually andmay therefore not be unique. Under coordinated assignment model, GINuses a combination of PLMN ID and NID and is assigned using one of thefollowing two options: 1) The GIN is assigned such that the NID isglobally unique (e.g., using IRNA Private Enterprise Numbers)independent of the PLMN ID used; or 2) The GIN is assigned such that thecombination of the NID and the PLMN ID is globally unique.

In the example of FIG. 4 , NG-RAN 401 provides access to SNPNs andbroadcasts the following information (410): One or multiple PLMN IDs andList of NIDs per PLMN ID identifying the non-public networks the NG-RANprovides access to (e.g., SNPN 1 and SNPN 2). Optionally, thebroadcasted information further includes the following: a human-readablenetwork name (HRNN) per SNPN; an indication per SNPN of whether accessusing credentials from a Credentials Holder is supported; a list ofsupported Group IDs for Network Selection (GINs) per SNPN (e.g., GIN 1and GIN 2); and an indication per SNPN of whether the SNPN allowsregistration attempts from UEs that are not explicitly configured toselect the SNPN, i.e., UEs that do not have any SNPN ID (PLMN ID+NID)nor GIN broadcast by the SNPN in the Credentials Holder controlledprioritized lists of preferred SNPNs/GINs.

FIG. 5A illustrates an example of an SNPN-enabled UE that is configuredwith SNPN subscription information for each subscribed SNPN. In theexample of FIG. 5A, an SNPN-enabled UE 501 is configured with the 2 SNPNsubscriptions as depicted by 510/520 for each subscribed SNPN: SNPN ID(PLMN ID+NID) of the subscribed SNPN (e.g., SNPN 1 in Entry 1 of the“list of subscriber data”, SNPN 2 in Entry 2 of the “list of subscriberdata”); and Subscription identifier (SUPI) and credentials for each ofthe subscribed SNPN. If the UE supports access to an SNPN usingcredentials from a Credentials Holder for each subscribed SNPN: 1) Usercontrolled prioritized list of preferred SNPNs (e.g., SNPN 111, SNPN 112for Entry 1; SNPN 211, SNPN 212 for Entry 2); 2) Credentials Holdercontrolled prioritized list of preferred SNPNs (e.g., SNPN 121, SNPN 122for Entry 1; SNPN 221, SNPN 222 for Entry 2); and 3) Credentials Holdercontrolled prioritized list of GINs (e.g., GIN131, GIN132 for Entry 1;GIN 231, GIN 232 for Entry 2).

FIG. 5B illustrates an example of an SNPN-enabled UE that is configuredwith 2 PLMN subscriptions (i.e., 2 USIMs). An SNPN-enabled UE thatsupports access to an SNPN using credentials from a Credentials Holderand that is equipped with a PLMN subscription (USIM) may additionally beconfigured with information for SNPN selection and registration usingthe PLMN subscription (in SNPN access mode). For example, PLMNsubscription 1 is associated with information for SNPN selection 530: 1)User controlled prioritized list of preferred SNPNs (e.g., SNPN 311,SNPN 312); 2) Credentials Holder controlled prioritized list ofpreferred SNPNs (e.g., SNPN 321, SNPN 322); and 3) Credentials Holdercontrolled prioritized list of GINs (e.g., GIN 331, GIN 332). Similarly,PLMN subscription 2 is associated with information for SNPN selection540: 1) User controlled prioritized list of preferred SNPNs (e.g., SNPN411, SNPN 412); 2) Credentials Holder controlled prioritized list ofpreferred SNPNs (e.g., SNPN 421, SNPN 422); and 3) Credentials Holdercontrolled prioritized list of GINs (e.g., GIN 431, GIN 432).

A subscription of an SNPN is either identified by a SUPI containing anetwork-specific identifier that takes the form of a Network AccessIdentifier (NAI). The realm part of the NAI may include the NID of theSNPN; or identified by a SUPI containing an IMSI. For an SNPN-enabled UEwith SNPN subscription, the Credentials Holder controlled prioritizedlists of preferred SNPNs/GINs may be updated by the CH using theSteering of Roaming (SoR) procedure. For an SNPN-enabled UE with PLMNsubscription, the Credentials Holder controlled prioritized lists ofpreferred SNPNs/GINs may be updated by the CH using the Steering ofRoaming (SoR) procedure. When the Credentials Holder updates a UE withthe Credentials Holder controlled prioritized lists of preferred SNPNsand GINs, the UE may perform SNPN selection again, e.g., to potentiallyselect a higher prioritized SNPN.

FIG. 6 illustrates Network selection in SNPN access mode with automaticSNPN network selection and manual SNPN network selection. AnSNPN-enabled UE 601 supports to access SNPN (in SNPN access mode). Whenthe UE is set to operate in SNPN access mode the UE only selects andregisters with SNPNs. When a UE is set to operate in SNPN access modethe UE does not perform normal PLMN selection procedures. There are twoSNPN network selection procedures: an automatic SNPN network selectionprocedure and a manual SNPN network selection procedure.

Under automatic SNPN network selection, UE selects and attemptsregistration on available and allowable SNPNs in the following order: 1)the SNPN the UE was last registered with (if available) or theequivalent SNPN (if available); 2) the subscribed SNPN, which isidentified by the SNPN ID (PLMN ID+NID) for which the UE has SUPI andcredentials; 3) if the UEs supports access to an SNPN using credentialsfrom a Credentials Holder then the UE continues by selecting andattempting registration on available and allowable SNPNs which broadcastthe indication that access using credentials from a Credentials Holderis supported in the following order: a) SNPNs in the user controlledprioritized list of preferred SNPNs (in priority order); b) SNPNs in theCredentials Holder controlled prioritized list of preferred SNPNs (inpriority order); c) SNPNs, which additionally broadcast a GIN containedin the Credentials Holder controlled prioritized list of preferred GINs(in priority order); and 4) SNPNs, which additionally broadcast anindication that the SNPN allows registration attempts from UEs that arenot explicitly configured to select the SNPN, i.e. the broadcasted SNPNID or GIN is not present in the Credentials Holder controlledprioritized lists of preferred SNPNs/GINs in the UE.

In the example of FIG. 6 , UE 601 was registered to SNPN 100, thesubscribed SNPN is SNPN 1 and has three lists for credentials. The Usercontroller prioritized list of preferred SNPNs includes SNPN 111, SNPN112; the Credential Holder controlled prioritized list of preferredSNPNs includes SNPN 121, SNPN 122; the Credential Holder controlledprioritized list of GINs includes GIN 131, GIN 132. There are a list ofSNPNs/GINs (broadcasted by one or more NG-RANs) available in current UElocation e.g., SNPN 100, SNPN 1, SNPN 111, SNPN 112, SNPN 121, SNPN300/GIN 131. UE 601 selects and attempts to register to an SNPN in thefollowing preference/priority order: SNPN 100, SNPN 1, SNPN 111, SNPN112, SNPN 121, and SNPN 300 which also broadcasts GIN 131.

Under manual network selection, UEs operating in SNPN access modeprovide to the user the list of SNPNs (each is identified by a PLMN IDand NID) and related human-readable network names (if available) of theavailable SNPNs the UE has respective SUPI and credentials for. If theUEs supports access to an SNPN using credentials from a CredentialsHolder, the UE also presents available SNPNs which broadcast the “accessusing credentials from a Credentials Holder is supported” indication andthe human-readable names related to the SNPNs (if available). When a UEperforms Initial Registration to an SNPN, the UE shall indicate theselected PLMN ID and NID as broadcast by the selected SNPN to NG-RAN.NG-RAN shall inform the AMF of the selected PLMN ID and NID.

If a UE performs the registration or service request procedure in anSNPN identified by a PLMN ID and a self-assigned NID and there is nosubscription for the UE, then the AMF shall reject the UE with anappropriate cause code to temporarily prevent the UE from automaticallyselecting and registering with the same SNPN. If a UE performs theregistration or service request procedure in an SNPN identified by aPLMN ID and a coordinated assigned NID and there is no subscription forthe UE, then the AMF shall reject the UE with an appropriate cause codeto permanently prevent the UE from automatically selecting andregistering with the same SNPN. If a UE performs the registration in anSNPN using credentials from a Credentials Holder and UE is notauthorized to access that specific SNPN, then the UDM can reject the UEwhich results in AMF rejecting the registration request from the UE withan appropriate cause code to prevent the UE from selecting andregistering with the same SNPN using credentials from the CredentialsHolder. In order to prevent access to SNPNs for authorized UE(s) in thecase of network congestion/overload, Unified Access Control informationis configured per SNPN (i.e., as part of the subscription informationthat the UE has for a given SNPN) and provided to the UE.

PNI-NPN (CAG)

PNI-NPNs (CAGs) are NPNs made available via PLMNs e.g., by means ofdedicated DNNs, or by one (or more) Network Slice instances allocatedfor the NPN. The existing network slicing functionalities apply. When aPNI-NPN is made available via a PLMN, then the UE shall have asubscription for the PLMN in order to access PNI-NPN. A Closed AccessGroup (CAG) identifies a group of subscribers who are permitted toaccess one or more CAG cells associated to the CAG. CAG is used for thePNI-NPNs to prevent UE(s), which are not allowed to access the NPN viathe associated cell(s), from automatically selecting and accessing theassociated CAG cell(s). A CAG is identified by a CAG Identifier which isunique within the scope of a PLMN ID. A CAG cell broadcasts one ormultiple CAG Identifiers per PLMN. A CAG cell may in addition broadcasta human-readable network name (HRNN) per CAG Identifier.

To use CAG, the UE, that supports CAG as indicated as part of the UE5GMM Core Network Capability, may be pre-configured or (re)configuredwith the following CAG related information. If the UE supports CAG, theUE can be provisioned by the network with a CAG related configuration(e.g., (enhanced) CAG information (list) containing list of allowed CAGsper PLMN)), consisting of zero or more entries, each entry containing a)a PLMN ID, b) an “Allowed CAG list” having zero or more CAG-IDs, and c)an optional “indication that the UE is only allowed to access 5GS viaCAG cells”. The HPLMN may (pre-)configure or re-configure a UE with theabove CAG related configuration using the UE Configuration Updateprocedure or other 5GMM procedures (e.g., registration procedure orservice procedure). The above CAG related configuration is provided bythe HPLMN on a per PLMN basis. In a PLMN the UE shall only consider theCAG information provided for this PLMN.

When the subscribed CAG related configuration changes, UDM sets a CAGinformation Subscription Change Indication and sends it to the AMF. TheAMF shall provide the UE with the CAG related configuration when the UDMindicates that the CAG related configuration within the Access andMobility Subscription data has been changed. When AMF receives theindication from the UDM that the CAG related configuration within theAccess and Mobility Subscription has changed, the AMF uses the CAGrelated configuration received from the UDM to update the UE. Once theAMF updates the UE and obtains an acknowledgment from the UE, the AMFinforms the UDM that the update was successful and the UDM clears theCAG information Subscription Change Indication flag. The AMF may updatethe UE using either the UE Configuration Update procedure afterregistration procedure is completed, or by including the new CAG relatedconfiguration in the Registration Accept or in the Registration Rejector in the Deregistration Request or in the Service Reject.

When the UE is roaming and the Serving PLMN provides CAG relatedconfiguration, the UE shall update only the CAG related configurationprovided for the Serving PLMN, while the stored CAG relatedconfiguration for other PLMNs is not updated. When the UE is not roamingand the HPLMN provides CAG related configuration, the UE shall updatethe CAG related configuration stored in the UE with the received CAGrelated configuration for all the PLMNs. The UE shall store the latestavailable CAG related configuration for every PLMN for which it isprovided and keep it stored when the UE is de-registered or switchedoff. The CAG related configuration is only applicable with 5GS.

For network and cell selection, the CAG cell shall broadcast informationsuch that only UEs supporting CAG are accessing the cell; cells areeither CAG cells or normal PLMN cells (non CAG cells). For accesscontrol, in order to prevent access to NPNs for authorized UE(s) in thecase of network congestion or overload, existing mechanisms defined forControl Plane load control, congestion and overload control can be used,as well as the access control and barring functionality, or UnifiedAccess Control using the access categories can be used. The MobilityRestrictions shall be able to restrict the UE's mobility according tothe Allowed CAG list (if configured in the subscription) and include anindication whether the UE is only allowed to access 5GS via CAG cells(if configured in the subscription).

During transition from CM-IDLE to CM-CONNECTED and during Registrationafter connected mode mobility from E-UTRAN to NG-RAN, the AMF shallverify whether UE access is allowed by Mobility Restrictions. If the UEis accessing the 5GS via a CAG cell and if at least one of the CAGIdentifier(s) received from the NG-RAN is part of the UE's Allowed CAGlist, then the AMF accepts the NAS request. If the UE is accessing the5GS via a CAG cell and if none of the CAG Identifier(s) received fromthe NG-RAN are part of the UE's Allowed CAG list, then the AMF rejectsthe NAS request and the AMF can include CAG related configuration in theNAS reject message. The AMF then release the NAS signaling connectionfor the UE by triggering the AN release procedure. If the UE isaccessing the 5GS via a non-CAG cell and the UE's subscription containsan indication that the UE is only allowed to access 5GS via CAG cells,then the AMF rejects the NAS request and the AMF should include CAGrelated configuration in the NAS reject message. The AMF then releasethe NAS signaling connection for the UE by triggering the AN releaseprocedure.

During transition from RRC Inactive to RRC Connected state, when the UEinitiates the RRC Resume procedure for RRC Inactive to RRC Connectedstate transition in a CAG cell, NG-RAN shall reject the RRC Resumerequest from the UE if none of the CAG Identifiers supported by the CAGcell are part of the UE's Allowed CAG list according to the MobilityRestrictions received from the AMF or if no Allowed CAG list has beenreceived from the AMF. When the UE initiates the RRC Resume procedurefor RRC Inactive to RRC Connected state transition in a non-CAG cell,NG-RAN shall reject the UE's Resume request if the UE is only allowed toaccess CAG cells according to the Mobility Restrictions received fromthe AMF.

During connected mode mobility procedures within NG-RAN, i.e., handoverprocedures, source NG-RAN shall not handover the UE to a target NG-RANnode if the target is a CAG cell and none of the CAG Identifierssupported by the target CAG cell are part of the UE's Allowed CAG listin the Mobility Restriction List or if no Allowed CAG list has beenreceived from the AMF. Source NG-RAN shall not handover the UE to anon-CAG cell if the UE is only allowed to access CAG cells based on theMobility Restriction List. If the target cell is a CAG cell, targetNG-RAN shall reject the N2 based handover procedure if none of the CAGIdentifiers supported by the CAG cell are part of the UE's Allowed CAGlist in the Mobility Restriction List or if no Allowed CAG list has beenreceived from the AMF. If the target cell is a non-CAG cell, targetNG-RAN shall reject the N2 based handover procedure if the UE is onlyallowed to access CAG cells based on the Mobility Restriction List. Whenthe AMF receives the Nudm_SDM_Notification from the UDM and the AMFdetermines that the Allowed CAG list or the indication whether the UE isonly allowed to access CAG cells have changed, AMF shall update theMobility Restrictions in the UE and NG-RAN accordingly under theconditions.

FIG. 7A illustrates a first embodiment of network and cell selection andaccess control of CAG cells for PNI-NPN (CAG), where access to a CAGcell is accepted. In the example of FIG. 7A, UE 711 is configured with aCAG related configuration (e.g., CAG information list 710), comprising alist of entries. For each entry, it comprises a) a PLMN ID, b) an“Allowed CAG list” having zero or more CAG-IDs, and c) an optional“indication that the UE is only allowed to access 5GS via CAG cells”.For example, entry 1 comprises PLMN 111, and an allowed CAG list withCAG-ID AAA and BBB. Through 5GC/AMF and NG-RAN, a CAG cell broadcastsone or more CAG-IDs per PLMN, e.g., CAG-ID AAA and CCC can be accessedvia the CAG cell 712. As a result, UE 711 can access the CAG cell 712 inPLMN 111.

FIG. 7B illustrates a second embodiment of network and cell selectionand access control of non-CAG cells, where access to a PLMN is accepted.In the example of FIG. 7B, UE 721 is configured with a CAG relatedconfiguration (e.g., CAG information list 720), comprising a list ofentries. For each entry, it comprises a) a PLMN ID, b) an “Allowed CAGlist” having zero or more CAG-IDs, and c) an optional “indication thatthe UE is only allowed to access 5GS via CAG cells”. For example, entry1 comprises PLMN 111, and an allowed CAG list with CAG-ID AAA and BBB.In addition, there is no indication in entry 1 that indicates the UE isonly allowed to access 5GS via CAG cells. Through 5GC/AMF and NG-RAN722, UE 721 finds non-CAG cell in PLMN 111 (i.e., no CAG IDs arebroadcasted by the cell 722). Since UE 721 is allowed to access 5GS vianon-CAG cell, as a result, UE 721 can access the non-CAG cell 722 inPLMN 111.

FIG. 8A illustrates a first embodiment of network and cell selection andaccess control of CAG cells for PNI-NPN (CAG), where access to a CAGcell is rejected. In the example of FIG. 8A, UE 811 is configured with aCAG related configuration (e.g., CAG information list 810), comprising alist of entries. For each entry, it comprises a) a PLMN ID, b) an“Allowed CAG list” having zero or more CAG-IDs, and c) an optional“indication that the UE is only allowed to access 5GS via CAG cells”.For example, entry 1 comprises PLMN 111, and an allowed CAG list withCAG-ID AAA and BBB. Through 5GC/AMF and NG-RAN 812, a CAG cellbroadcasts one or more CAG-IDs per PLMN, e.g., CAG-ID CCC and DDD.However, neither CAG-ID CCC nor CAG-ID DDD are in the “Allowed CAGlist”. As a result, UE 811 cannot access this CAG cell CCC/DDD of PLMN111.

FIG. 8B illustrates a second embodiment of network and cell selectionand access control of CAG cells for PNI-NPN (CAG), where access to aPLMN is rejected. In the example of FIG. 8B, UE 821 is configured with aCAG related configuration (CAG information list 820), comprising a listof entries. For each entry, it comprises a) a PLMN ID, b) an “AllowedCAG list” having zero or more CAG-IDs, and c) an optional “indicationthat the UE is only allowed to access 5GS via CAG cells”. For example,entry 1 comprises PLMN 111, and an allowed CAG list with CAG-ID AAA andBBB. In addition, there an indication in entry 1 that indicates the UEis only allowed to access 5GS via CAG cells. Through 5GC/AMF and NG-RAN822, UE 821 finds non-CAG cell in PLMN 111 (i.e., no CAG cell IDs arebroadcasted by the cell 822). Since UE 821 is not allowed to access 5GSvia non-CAG cell, as a result, UE 821 cannot access the non-CAG cell 822in PLMN 111.

NPN (as Hosting Network) Providing Access for Localized Services.

Local or localized service is localized (i.e., provided atspecific/limited area and/or can be bounded in time). The service can berealized via applications (e.g., live or on-demand audio/video stream,electric game, IMS, etc.), or connectivity (e.g., UE to UE, UE to DataNetwork, etc.). A localized service provider is an application provideror network operator who make their services localized and to be offeredto end users via a hosting network, which is a network that providesaccess for local or Localized services. A home network is network owningthe current in use subscription or credential of the UE. Home networkcan be either Home-PLMN or Subscribed-SNPN. An SNPN may support primaryauthentication and authorization of UEs that use credentials from aCredentials Holder using AUSF and UDM. The Credentials Holder may beHome-PLMN or Subscribed-SNPN. For SNPN as hosting network, home networkcan be regarded as CH. For PNI-NPN (CAG) as hosting network, homenetwork can be regarded as (Home-)PLMN. For providing Localized servicesto UE, UE needs to be able to discover, select and access a NPN (ashosting network) providing access for the Localized services. Thediscovery mechanism is based on provisioning/(pre-)configuring/signalingthe UE with appropriate information.

FIG. 9A illustrates one example of UE to discover, select and access NPN(as hosting network) and receive localized services using validityinformation. When UE accesses the NPN (as Hosting network) using thesubscription/credentials of its home network, only two cases areconsidered. If Home network (/CH) is PLMN, the Hosting network can bePNI-NPN or SNPN. If Home network (/CH) is SNPN, the Hosting network canbe only SNPN. If the UE accesses the Hosting network using subscriptionsor credentials from the UE Home network, and the UE has multiplecredentials or subscriptions, the UE needs to determine which credentialor subscription to be used to access the Hosting network. Validityinformation or conditions information provided to the UE as part of thelocalized service information can be used to restrict the UE's access ofthe hosting network, including: (time and/or location) validityinformation or conditions information ((Time and/or Location:) duration,criteria, or restriction) associated with SNPN(ID) or GIN; and (timeand/or location) validity information/conditions ((Time and/orLocation:) duration, criteria, or restriction) associated withPNI-NPN/CAG-ID.

As depicted by 910, an SNPN-enabled UE is configured with the followinginformation for each subscribed SNPN: PLMN ID and NID (SNPN ID) of thesubscribed SNPN (e.g., SNPN 1); and Subscription identifier (SUPI) andcredentials for the subscribed SNPN. If the UE supports access to anSNPN using credentials from a Credentials Holder, then the UE is alsoconfigured with 1) User controlled prioritized list of preferred SNPNs(e.g., SNPN 111, SNPN 112); 2) Credentials Holder controlled prioritizedlist of preferred SNPNs (e.g., SNPN 121, SNPN 122, SNPN 123); and 3)Credentials Holder controlled prioritized list of GINs (e.g., GIN 131,GIN 132).

FIG. 9B illustrates another example of UE to discover, select and accessNPN (as hosting network) and receive localized services using validityinformation. For automatic network selection, in the case of SNPN (ashosting network) for Localized services, there can be associated (time(duration) and/or location (restriction)) validity information forSNPN(s) or GIN(s). For one example, as depicted by 910, (1) the existingCredentials Holder controlled prioritized list of preferred SNPNs (andGINs) can be extended with the (time and/or location) validityinformation or conditions information for each entry in the list; or asanother example depicted by 911, (2) there can be a (or more) new listtype defined to provide entries with validity information for SNPNs (andGINs) (ex: define new CH controlled prioritized lists of preferredSNPNs/GINs (for access localized service, where each entry contains anSNPN/GIN identity and/) including (optional) validityinformation/conditions).

As depicted by 910 or 911, SNPN 121 has associated time (duration)validity condition (the time duration (e.g., start and end time) inwhich the UE is allowed to access the SNPN 121) ofJanuary-1^(st)˜January-2^(nd), SNPN 123 has associated time validitycondition of January-1^(st)˜January-3^(rd), and GIN 131 has associatedtime (duration) validity condition of January-1^(st)˜January-3^(rd).Such time (duration) validity/conditions information are provided to theUE as part of the localized service information to restrict the UE'saccess of the (hosting network) Localized services. Thevalidity/conditions information can also optionally include locationvalidity/conditions information, which can be in the form of geolocationand/or TAI(s)/Cell(s) (of serving network (serving PLMN/PNI-NPN orserving SNPN)), the location validity/conditions information can be usedto assist the UE to know where to start searching for SNPNs hostingnetworks.

FIG. 9C illustrates another example of UE to discover, select and accessNPN (as hosting network) and receive localized services usingvalidity/conditions information. For automatic network selection, in thecase of PNI-NPN with CAG, a CAG-ID (in the (enhanced/extended (allowed))CAG list) can be optionally associated with time validity/conditions orrestriction information (the time duration (e.g., start and end time) inwhich the UE is allowed to access the PNI-NPN/CAG) and/or locationvalidity/conditions or restriction information. Time duration and/orlocation validity/conditions or restriction may be provided togetherwith the CAG Identifier. For example, the ((enhance/extended) Allowed)CAG list can be provided to UE and AMF for enforcement, to make surethat UE not accessing the CAG cell outside of the time duration or(/and)outside of the allowed-location. The location validity/conditionsinformation can be in the form of geolocation and/or TAI(s)/Cell(s) (ofserving network (serving PLMN/PNI-NPN or serving SNPN)), the locationvalidity/conditions or restriction information can be used to assist theUE to know where to start searching for the PNI-NPN hosting networks.

Note that, as depicted by 920, the (time and/or location) validityinformation can be stored next to the CAG-ID (e.g., enhance/extend theoriginal allowed CAG list), or stored independently in the UE and isassociated to a (or more) CAG-ID; or as depicted by 921 there can be a(or more) new list type defined to provide entries with validityinformation for CAG(s). As depicted by 920, for example, the((enhanced/extended) Allowed) CAG list for PLMN 111 includes CAG AAA,BBB, and CCC. CAG-ID AAA is associated with time validity information ofJanuary-1^(st)˜January-3^(rd), and CAG-ID CCC is associated with timevalidity information of January-1^(st)˜January-2^(nd). Similar logicapplies for location validity, if any. Such (time and location) validityconditions are provided to the UE as part of the localized serviceinformation to restrict the UE's access of the localized services(hosting network).

FIG. 10A illustrates a first example of accessing localized services viaSNPN (as a hosting network), where access is accepted. In the example ofFIG. 10A, UE 1001 is configured with the following SNPN subscription:the subscribed SNPN=SNPN 1, Credentials Holder controlled prioritizedlist of preferred SNPNs, which includes SNPN 121, SNPN 122, and SNPN123. SNPN 121 is associated with time validity condition ofJanuary-1^(st)˜January-2^(nd), and SNPN 123 is associated with timevalidity condition of January-1^(st)˜January-3^(rd). Through 5GC/AMF andNG-RAN 1002, SNPN 123 broadcasts its SNPN ID==123, with an indication ofaccess using credentials from a Credentials Holder is supported. SinceUE 1001 is subscribed to SNPN 1, and SNPN 123 is included as a preferredSNPN in the entry of “list of subscriber data” for SNPN1, UE 1001 mayattempt to access SNPN 123 using credentials from SNPN 1. Since a timevalidity condition is associated with SNPN 123, UE 1001 needs todetermine whether such time validity condition is satisfied before theaccess. UE 1001 checks the current time of January 2^(nd), which isinside the time period of January-1^(st)˜January-3^(rd). As a result, UE1001 can access SNPN 123 using credentials from the (subscribed) SNPN 1.SNPN 123 is the localized service provider. SNPN 123 is the hostingnetwork. SNPN 1 is the credential holder. (If location validityinformation is available, in this example we assume location validity ismet per the location validity information.)

FIG. 10B illustrates a second example of accessing localized servicesvia SNPN (as a hosting network), where access is not allowed (if UEtries to access, the network will reject). In the example of FIG. 10B,UE 1001 is configured with the following SNPN subscription: thesubscribed SNPN=SNPN 1, a Credentials Holder controlled prioritized listof preferred SNPNs, which includes SNPN 121, SNPN 122, and SNPN 123.SNPN 121 is associated with time validity condition ofJanuary-1^(st)˜January-2^(nd), and SNPN 123 is associated with timevalidity condition of January-1^(st)˜January-3^(rd). Through 5GC/AMF andNG-RAN 1002, the hosting network SNPN 123 broadcasts its SNPN ID==123,with an indication of access using credentials from a Credentials Holderis supported. Since UE 1001 is subscribed to SNPN 1, and SNPN 123 isincluded as a preferred SNPN in the entry of “list of subscriber data”for SNPN1, UE 1001 may attempt to access SNPN 123. However, since a timevalidity condition is associated with SNPN 123, UE 1001 also needs toadditionally determine whether such time validity condition is satisfiedbefore the access. UE 1001 checks the current time of January 4^(th),which is outside the time period of January-1^(st)˜January-3^(rd). As aresult, UE 1001 cannot access SNPN 123 using credentials from SNPN 1.

FIG. 11A illustrates a first example of accessing localized services viaPNI-NPN with CAG (as a hosting network), where access is accepted. Inthe example of FIG. 11A, UE 1101 is configured with a CAG relatedconfiguration 1110, comprising a list of entries. For example, entry 1comprises PLMN 111, and an enhanced or extended allowed CAG list withCAG-ID AAA, BBB and CCC. CAG AAA is associated with time validitycondition of January-1^(st)˜January-3^(rd), and CAG CCC is associatedwith time validity condition of January-1^(st)˜January-2^(nd). Through5GC/AMF and NG-RAN 1102, a CAG cell broadcasts one or more CAG-IDs perPLMN, e.g., CAG-ID AAA of PLMN 111. Since a time validity condition isassociated with CAG AAA, UE 1001 needs to determine whether such timevalidity condition is satisfied before the access. UE 1101 checks thecurrent time of January 2^(nd), which is inside the time period ofJanuary-1^(st)˜January-3^(rd) associated with CAG AAA. As a result, UE1101 can access CAG AAA of PLMN 111 via the cell. (PNI-NPN/CAG-AAA isthe service provider, PNI-NPN/CAG-AAA is the hosting network, Home PLMNof the currently used USIM is the home network, and Home PLMN is thecredential holder.) (If location validity information is available, inthis example, we assume location validity is met per the locationvalidity information.)

FIG. 11B illustrates a second example of accessing localized servicesvia PNI-NPN with CAG (as a hosting network), where access is rejected.In the example of FIG. 11B, UE 1101 is configured with a CAG relatedconfiguration 1110, comprising a list of entries. For example, entry 1comprises PLMN 111, and an enhanced or extended allowed CAG list withCAG-ID AAA, BBB and CCC. CAG AAA is associated with time validitycondition of January-1^(st)˜January-3^(rd), and CAG CCC is associatedwith time validity condition of January-1^(st)˜January-2^(nd). Through5GC/AMF and NG-RAN 1102, a CAG cell broadcasts one or more CAG-IDs perPLMN, e.g., CAG-ID AAA and CAG-ID CCC of PLMN 111. Since time validityconditions are associated with CAG AAA and CCC, UE 1101 needs todetermine whether such time validity conditions are satisfied before theaccess. UE 1101 checks the current time of January 4th, which is outsidethe time period of January-1^(st)˜January-3^(rd) associated with CAGAAA, and outside the time period of January-1^(st)˜January-2^(nd)associated with CAG CCC. As a result, UE 1101 cannot access CAG cell AAAor CCC.

Emergency Service

When a PNI-NPN is made available via a PLMN, a UE shall have asubscription for the PLMN in order to access the PNI-NPN. A ClosedAccess Group (CAG) identifies a group of subscribers who are permittedto access one or more CAG cells associated to the CAG. CAGs may be usedto apply access control for the PNI-NPN. For a PNI-NPN (as hostingnetwork) that provides localized services, a CAG cell of the PNI-NPNhosting network may be associated with validity or restrictioninformation, e.g., time and/or location validity or restrictioncriteria. As a result, the condition in determining whether a UE canaccess a CAG cell may change. For example, if a CAG-ID of a PLMN isassociated with a validity or restriction information and the validityor restriction criteria are not met, then a CAG cell broadcasting theCAG-ID cannot be accessed by the UE even if the CAG-ID is listed in aCAG related configuration (e.g., enhanced/extended Allowed CAG list) andbroadcasted by the PLMN.

If the UE supports accessing localize services via PNI-NPN with CAG (asa hosting network), the UE maintains a CAG related configuration. Thenetwork (AMF) also maintains a most-updated CAG related configurationfor the UE. If the UE maintained CAG related configuration may not besync with the most-updated CAG related configuration. When the UEselects a CAG cell and established a NAS connection, the network may notregard the current serving cell as a suitable cell, and may only providelimited service to the UE. However, if the UE has an emergency PDUsession, then the network cannot reject UE's normal service request andcan only release UE's non-emergency PDU session (on 3GPP access).

In accordance with one novel aspect, a method of handling a servicerequest from a UE camped on a CAG cell with emergency PDU session isproposed, where the UE is not authorized to access the current CAG cell.When the UE-maintained CAG related configuration is not synchronizedwith the NW-maintained CAG related configuration, the UE may try toaccess a CAG cell and sends a NAS service request, but the NW maydetermine that the CAG cell is not suitable. Because the UE has anexisting emergency PDU session, the network will accept the NAS servicerequest, and locally releases all non-emergency PDU sessions associatedwith 3GPP access. Specifically, the network will locally release SA PDUsessions associated with 3GPP access, or MA PDU sessions with only 3GPPaccess user-plane resources, or 3GPP user-plane resources of MA PDUsessions with both 3GPP and non-3GPP access user-plane resources. In oneembodiment, the NAS request message is a SERVICE REQUEST message or aREGISTRATION REQUEST message, and the NAS accept message is a SERVICEACCEPT message or a REGISTRATION ACCEPT message.

FIG. 12 illustrates a sequence flow between a UE and a 5GS when UE isaccessing a CAG cell with un-synchronized CAG related configuration andemergency PDU session in accordance with one novel aspect. In step 1211,UE 1201 camped on a CAG cell (as a suitable cell) in a PLMN andestablishes an N1 NAS signaling connection. The UE maintains a CAGrelated configuration, including a list of allowed CAG-IDs of the PLMN.In step 1212, UE 1201 establishes one or more normal (non-emergency) PDUsessions. In step 1213, UE 1201 establishes one more emergency PDUsessions. In step 1214, the NAS connection is released, e.g., due to notraffic for a long time. In step 1221, UE 1201 performs cell selectionand selects a new CAG cell in the PLMN. For example, the new CAG cellbroadcasts a first CAG ID of the PLMN. The first CAG ID is included inthe UE-maintained CAG related configuration, and the validity criteriaassociated with the first CAG ID are met.

In step 1222, in order to establish NAS signaling connection, UE 1201sends an uplink NAS message to 5GS (AMF) 1202, e.g., a REGISTRATIONREQUEST, or a SERVICE REQUEST message to the AMF. In step 1231, the AMFreceives the NAS message from UE 1201 via the new CAG cell. However, theAMF determines, that based on the NW-maintained CAG relatedconfiguration, the first CAG-ID is not included, or the validitycriteria associated with the first CAG ID are not met. This may bebecause of some inconsistency between the UE-maintained CAG relatedconfiguration and the NW-maintained CAG related configuration. As aresult, the AMF determines that the new CAG cell selected by the UE isnot a suitable cell. In step 1232, the AMF also knows that the UE has anestablished emergency PDU session.

In response to the determination of steps 1231 and 1232, the 5GS (AMF)1202 sends a downlink NAS message to UE 1201, e.g., a REGISTRATIONACCEPT, or A SERVICE ACCEPT message. In step 1242, the AMF releases allnon-emergency PDU sessions that are associated with 3GPP access. Thosenon-emergency PDU sessions include: 1) a single access PDU session over3GPP access; 2) a multiple access PDU session with only 3GPP access userplane resources; or 3) a multiple access PDU session with both 3GPP andnon-3GPP user plane resources (only the user plane resources on 3GPP arereleased locally). The existing emergency PDU session is kept for theUE.

FIG. 13 illustrates an example of handling a service request from a UEcamped on a CAG cell with emergency PDU session, where the UE is notauthorized to access the current CAG cell. In general, a CAG relatedconfiguration includes zero or more entries, each entry containing a) aPLMN ID, b) an (Allowed) CAG list having zero or more CAG-IDs, and c) anoptional indication that the UE is only allowed to access 5GS via CAGcells. In the example of FIG. 13 , UE 1301 maintains a CAG relatedconfiguration 1310 for accessing services via PNI-NPN with CAG. The(Allowed) CAG list in an entry of the CAG related configuration 1310comprises a list of CAG-IDs for PLMN 222 including CAG 21 and CAG 22.

Through 5GC/AMF and NG-RAN, a CAG cell 1302 broadcasts one or moresupported CAG-IDs per PLMN, e.g., CAG-ID 20, 21, 22, and 23 of PLMN 222.Since CAG 21 and CAG 22 are broadcasted and supported by the CAG cell1302 and are included in the (Allowed) CAG list of the CAG relatedconfiguration 1310, UE 1301 assumes that it can access CAG 21 or CAG 22of PLMN 222 via the CAG cell 1302. Later on, however, the 5GC (AMF) mayhave an updated CAG related configuration for UE 1301, e.g. CAG relatedconfiguration 1320 comprising a list of (Enhanced/Extended) (Allowed)CAG-IDs for PLMN 222 including CAG 21 and CAG 22. CAG 21 is associatedwith validity or restriction information 1321, e.g., time validitycriteria of January-1 20:00 pm-22:00 pm, and CAG 22 is associated withvalidity or restriction information 1322, e.g., time validity criteriaof January-2 20:00 pm-22:00 pm.

If the current time is January 3^(rd), which is outside the time periodof January-1 20:00 pm-22:00 pm associated with CAG 21, and also outsidethe time period of January-2 20:00 pm-22:00 pm associated with CAG 22.Therefore, none of the CAG-IDs configured with the time validity orrestriction information whose validity or restriction criteria are met(e.g., not matching with UE's current time). As a result, based on theupdated CAG related configuration 1320, UE 1301 cannot access CAG 21 orCAG 22 of PLMN 222 via the CAG cell 1302. The 5GC AMF thus determinesthat the CAG cell 1302 is not a suitable cell. However, since UE 1301has an existing emergency PDU session, it thus needs to stay in thecurrent cell and continue with data service on the emergency PDUsession. When UE 1301 sends an uplink NAS request to the network, the5GC AMF accepts the NAS request, and locally releases all non-emergencyPDU sessions with 3GPP access.

FIG. 14 is a flow chart of a method for handling a service request froma UE camped on a CAG cell with emergency PDU session, where the UE isnot authorized to access the current CAG cell in accordance with onenovel aspect. In step 1401, a network entity (AMF) receives a non-accessstratum (NAS) request message from a user equipment (UE), wherein the UEis camped on a Closed Access Group (CAG) cell. In step 1402, the AMFdetermines the CAG cell is not suitable for the UE based on anetwork-maintained CAG related configuration, wherein every CAG-IDsupported by the CAG cell and included in the network-maintained CAGrelated configuration is associated with validity information, andwherein all corresponding validity criteria are not met. In step 1403,the AMF transmits a NAS accept message to the UE when the UE has anemergency PDU session. In step 1404, the AMF releases all non-emergencyPDU sessions with user-plane resources established over 3GPP access orreleases user-plane resources established over 3GPP access ofcorresponding non-emergency PDU session. Specifically, the network willlocally release SA non-emergency PDU sessions associated with 3GPPaccess, or MA PDU sessions with only 3GPP access user-plane resources,or 3GPP user-plane resources of MA PDU sessions with both 3GPP andnon-3GPP access user-plane resources. In one embodiment, the NAS requestmessage is a SERVICE REQUEST message or a REGISTRATION REQUEST message,and the NAS accept message is a SERVICE ACCEPT message or a REGISTRATIONACCEPT message.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

What is claimed is:
 1. A method, comprising: receiving a non-accessstratum (NAS) request message from a user equipment (UE) by a networkentity, wherein the UE is camped on a Closed Access Group (CAG) cell;determining every CAG-ID supported by the CAG cell and included in theallowed CAG list is associated with validity information, and whereinall corresponding validity criteria of every CAG-ID are all not met;transmitting a NAS accept message to the UE when the UE has an emergencyPDU session; and releasing all non-emergency PDU sessions.
 2. The methodof claim 1, wherein the NAS request message is a SERVICE REQUEST messageor a REGISTRATION REQUEST message, wherein the NAS accept message is aSERVICE ACCEPT message or a REGISTRATION ACCEPT message.
 3. The methodof claim 1, wherein a non-emergency PDU session comprising a singleaccess non-emergency PDU session associated with 3GPP access.
 4. Themethod of claim 1, wherein a non-emergency PDU session comprising amulti-access PDU session with user-plane resources established only on3GPP access.
 5. The method of claim 1, wherein a non-emergency PDUsession comprising a multi-access PDU session with user-plane resourcesestablished on 3GPP access and on non-3GPP access, and wherein thenetwork entity releases the user-plane resource established on 3GPPaccess without releasing the MA PDU session.
 6. The method of claim 1,wherein the network entity does not release any single access PDUsession associated with non-3GPP access or any multi-access PDU sessionwith user-plane resources established only over non-3GPP access.
 7. Themethod of claim 1, wherein the validity information includes only timevalidity information, wherein the validity criteria are met if the timevalidity information matches a current time of the UE, and wherein thevalidity criteria are not met if the time validity information does notmatch the current time of the UE.
 8. The method of claim 1, wherein thevalidity information includes only location validity information,wherein the validity criteria are met if the location validityinformation matches a current location of the UE, and wherein thevalidity criteria are not met if the location validity information doesnot match the current location of the UE.
 9. The method of claim 1,wherein the validity information includes both time validity informationand location validity information, wherein the validity criteria are metif the time validity information matches a current time of the UE andthe location validity information matches a current location of the UE,and wherein the validity criteria are not met if the time validityinformation does not match the current time of the UE or the locationvalidity information does not match the current location of the UE. 10.A network entity, comprising: a receiver that receives a non-accessstratum (NAS) request message from a user equipment (UE), wherein the UEis camped on a Closed Access Group (CAG) cell; a control circuit thatdetermines every CAG-ID supported by the CAG cell and included in theallowed CAG list is associated with validity information, and whereinall corresponding validity criteria of every CAG-ID are all not met; atransmitter that transmits a NAS accept message to the UE when the UEhas an emergency PDU session; and a session management circuit thatreleases all non-emergency PDU sessions.
 11. The network entity of claim10, wherein the NAS request message is a SERVICE REQUEST message or aREGISTRATION REQUEST message, wherein the NAS accept message is aSERVICE ACCEPT message or a REGISTRATION ACCEPT message.
 12. The networkentity of claim 10, wherein a non-emergency PDU session comprising asingle access non-emergency PDU session associated with 3GPP access. 13.The network entity of claim 10, wherein a non-emergency PDU sessioncomprising a multi-access PDU session with user-plane resourcesestablished only on 3GPP access.
 14. The network entity of claim 10,wherein a non-emergency PDU session comprising a multi-access PDUsession with user-plane resources established on 3GPP access and onnon-3GPP access, and wherein the network entity releases the user-planeresource established on 3GPP access without releasing the MA PDUsession.
 15. The network entity of claim 10, wherein the network entitydoes not release any single access PDU session associated with non-3GPPaccess or any multi-access PDU session with user-plane resourcesestablished only over non-3GPP access.
 16. The network entity of claim10, wherein the validity information includes only time validityinformation, wherein the validity criteria are met if the time validityinformation matches a current time of the UE, and wherein the validitycriteria are not met if the time validity information does not match thecurrent time of the UE.
 17. The network entity of claim 10, wherein thevalidity information includes only location validity information,wherein the validity criteria are met if the location validityinformation matches a current location of the UE, and wherein thevalidity criteria are not met if the location validity information doesnot match the current location of the UE.
 18. The network entity ofclaim 10, wherein the validity information includes both time validityinformation and location validity information, wherein the validitycriteria are met if the time validity information matches a current timeof the UE and the location validity information matches a currentlocation of the UE, and wherein the validity criteria are not met if thetime validity information does not match the current time of the UE orthe location validity information does not match the current location ofthe UE.